'''
Created on 2012-9-19

@author: infear
'''
class Filter:
    def init(self):
        self.filterBlock=[]
        
    def filter(self,_list):
        return [x for x in _list if x not in self.filterBlock]
    
class MyFilter(Filter):
    def init(self):
        self.filterBlock=["a","b"]

myfilter=MyFilter()
myfilter.init()
print myfilter.filter("abc")
print isinstance(myfilter, MyFilter),isinstance(myfilter, Filter)            